Indicator



:[NnlcAToR Filed maken 21, 1939 2 Sheets-Shoe?l 1 Aug. 17, 1943l F. G.SCHWEISTHAL INDICATOR Filed Maren 21,. l193s 2 Sheets-Sheet 2 PatentedAug. 17,1943

. `INDICATOR Frederick G. schwisthal, chicago, nl., assigner' toStewart-Warner Corporation, Chicago, 111;,"

a corporation offVirgnia,

Application Mannen-1939, serialNo. 263,25of

L s claims. (o1. asi- The present invention relates'to indicatorsingeneral, and more particularly to-indicators f of the type known ascentrifugal tachometers.

In the conventional centrifugal tachometer comprising a rotatablegovernorshaft, a centrifugally actuated governor collar movable axiallyof the shaft in response to-variationsv in the speed of the rotation ofthe shaft, and apin and lever connection from the collar to indicatorpointer actuating gears, it isnecessrary,` in order to obtainsuflicient` pointermovement 'to keep -within va desired degree ofaccuracy, that the lever have a considerable range of angular movement.However, the greater the angular movement of the lever, the greater theinaccuracy of the readings because of certain angular and frictionalrelationships existing between the 'aforementioned collar, lever `andpin. Ordinarily, the pivot point of the pin supporting lever is locatedso that' the lever assumes approximately Iequal angles with respecttothe collar at both extremes of movement of the latter; When the leverisv at `one extreme or the other'and the lcollar is rotating in adirection toward the pivotpointof the lever, the frictional forcecreated by the rotation of the collar against vthe pin tends tothrustthe lever -in such a direction as toincrease the angle therebetweenandthe faceof the collar.

This thrust or jamming' results inflan undesired movement of the lever,and,'consequently, in in .f 'accurate readings-because 'the indicator ismoved,

It is the primary Olojieottof the' presentinvention to Vprovide'a new`andV improved indicator in 'l V which the aforesaid disadvantages aresubstanj tially eliminated.

A more specicobject ofthe present invention is vto provide a new andvimproved indicator :f

in' which the indicator pointer actuatingpin and lever-are movablethrough .the ,desired angular distances and yinvzhich the undesiredcramping or jamming withits resulting inaccuracy uis oloviated. -Y

-A'further object-of 4the present invention Yis Y to provide a new andimprovedindicator in which,

the frictional-forces created bythe rotation of the collar` against thepin are decreased Vand the une 5 5 of Fig. 2;

transmitted, not tovthe pin and` lever, but tothe frame ofl theindicator. l' e' Further objects and advantages of the present inventionwill become apparent from the ensuing description, in the course ofVwhich reference is had to the accompanying drawings, inwhich: Fig-,1 isa perspectivelviewfof the indicator;

Fig. 2 is an axial cross` sectional Yview through theindicator'takenalong the'line 2'-2 of Fig. 1; Fig; 3 is apartial transverse crosssectional view through a portion of the driving connection between aflexible shaft connecting the indicator governor shaft to a part, thespeed of'which -is to be indicated. The view is taken' along the line 33 of Fig. 2'; y v' v Fig. 4 is a transverse cross sectional view takenalong the line '1 -4.0i Fig. 2, illustrating the details of theconstruction of the adjustability of the lever of the pin and leverconnection which is located between the pointer Vand the governormechanism;:

Fig.'f5 is a partial top ,elevational View of the mechanism shown inFig. 4 and is taken along ,Fig.16 is a partial horizontal crosssectional viewtaken along .the line 6--6 of Fig. 4;

lig. 'Lisv a` partial transverse cross sectional view takenalong theline'l-.-l of Fig. 2, illustrating the minimum reading stop; Y

Fig. 8 is a View similar to Fig. 7 taken along the line aff-8,illustrating the hair spring utilized to return the pointer to itsminimum reading po-` sition and for maintaining the-'pinof the pin andlever connection in Contact with theshoe, and the shoe in contactwiththe face of .the governor colclar during normal operation of theindicator; an Y n Y Fig. 9 is a sectional viewof the shoe taken on theline 9,--9of Fig. 6.5` z

Reierringnow to Fig. l, it; may benoted that `the indicator lofthepresentv invention `comprises Y a housing l0, adapted tocontainthezvarious operating parts of a centrifugal tachometer. The

operating parts are rotated by a relatively long flexibleY shaft I2 at aspeediproportional to the speed,` of a partythe speed of which it isdesired tofhave .anl indicatiomsuch as apart of an air craft engine,` g.The indicator `comprises a pointer I4, adaptedY to-be rotated throughanlangle of 540 degrees andghavingAassociated therewith a dial i6carryingtwo suitably rsubdivided scales reading from Qvto 3,500R. P.-M.The scale is recognizable as beingof the type ordinarily used `inindicators utilized for indicating the speed. of

air craft engines.

Referring now morerparticularly to Figs. 2 and 4, it may be seen thatthe indicator l comprises a metallic frame I8 subdivided into twocomparttive to the governor shaft. The compartment 22 may be termed theindicator compartment for the reason that it houses certain of theindicator actuating gears as well as supports thepointer l il.

It may be Well to mention at this point 'that the governor mechanism perse corresponds in many details to apparatus that is welliknown in theart, and that the primary feature of the present invention resides inthe means provided for the. pilrposeofY eliminating,inaccuracies.resulting from the engagement of .the'collar 2.a with'the linkage andgear`- mechanism, indicated generally by reference character 3Q,utilized for transmite ting moyement of the collar to the indicator le.The details` of) the.'governor"meclfianism as well as of the.above-mentioned primary feature or the present invention Willbedescribed in greater detail after a description of the. driving connecetion between the goyernorshaft and the. iiex ible shaft l2.

The. shaft [.2 terminates in .a female plug memberY 3.2 (seeFigs. 2 and3) having a square bore and adapted to receivea driven member 3arotatably mounted upon a reduced portion 3&3 of the governor shaft andextending into a bore of a relatively small diameter located withinareduced portion 4:0.. of an end plate 42 comprising part of the.indicator frame I8.

.The driving connection. between member 34 and governor shaft 2'6. is'so constructed. andarrangedfthat when theitorque transmittedtherethrough in. either. direction 'of the driven rotation of the drivenmember is .less than a l predetermined value, the drive is resilient Vinnature, but when the torque. exceeds thev predetermined value, the drivebecomes "substantially positive.. The. driving connection. includes'.resilieni-l means, in this. casev ahelical: spring-f lid, havingassociated therewithwmeans preventing expansion or contractionthereof.'y beyond a prel determined extentvhen the torque transmittedtherethrough exceeds a certain value in a imanner to be describedshortly;- The driven member 341.` is constrained: against any;substantial arial movement .upon the. governorJshaft 2S by means of asmall annular spring 46, mounted in a groove formed nearthe extremeendofthe governor shaft,.and a shoulder A18-upon the governor shaftV againstwhich rabuts a radial harige v 5e, preferablyv formed as an integralpart ofthe driven member 34.

The drive. is .rendered substantially. positive when the torquetransmitted in one direction exceeds a predetermined Value by atubularmember 52', concentric with. respect to the governor shaft andspaced from the spring when the latter. is in arelaxedustateiagainst-which thespring is expanded. Thedrive is renderedsubstantiallypositive when the torque transmitted in the op'- posite directionexceeds a .predetermined value bypthe. contraction` of thespring IM.Yaboutv an intermediateportion. 54 ofthe governorJV shaft from which thespring is spaced when.. relaxed. The spring 44 has one end connectedto.the flange 5t of the driven member and the other end to a shoulder 5Sformed integrally with the governor shaft.

The governor shaft is'rotatably mounted in the indicator housing by ballbearings 53 housed Within the end plate 42 of the housing and ballbearings confined within an annular groove 60,

governor shaft by a plurality of weights 66, two of which are, s liowrnYeach pivotally mounted upon a pair of arms 68 and 10. The arms 68 arepivotally mounted upon a Weight support 12 adjustably secured directlyto the governor shaft by a screw 14. The arms 1) are pivotally securedto asesoria. weight support. 1,6.: ixoflly secured. to o governor sleevelll comprising a. pair of. spaced apartv collars; ai. and .8.2 and.consti-toting thoro-y with the governor collar 2 8... aol-lar isprefer-ably formed integrally with tbsY sleeve and maple of brass,while. the governor collar H- is preferably madeof; stool and providedwith .a substantially flat facs 9.4 'tot a. pur-poso. to be describedshortly.. It pressediipoathe sleeve The sleeve apo.- oollar. occupy asubstanially such. as. that iadioated 2 when the governor shaft is not.rotatingJ to. position it is. actuated. by a. governor snr-.ine 8.6surrounding the shaft andlooatod between the.. twosov- @mor Weight.supports. 1:2..- andv 16.-.

As hereinbefore stated. the. r .1ol31.la.1fyY Qbjeot; of the presentinvention. isy the transfer; of. Inovement of tbev oollarto. theindicator pointer a manner to. avoid. the inaccuracies. that might. becreated by the friotional forces, created by contact. of the governor.-oollar with the ordinary pin and lever connection utilised, toi transferthe movement ofthe collartotho indicati .e pointes. ThisA object i-.Sattained by.- interposinefbetween the collar 8.a andapin 8.8; which is.sunportedumn a. leyer. S0., ashoe. 8,2 pivotally secured to4 amlatiyel-ylong lever; 94.1. by a. pin 96;.. as. clearly illus; trated Fig.. 9..The shoe is. made of. bronneor othersuitable material.' and has.. aatsideadoptedta engage the flat face. 8510i the collar 8.12; with which.it is maintained in. .Q01-.1 apt, by suitable biasing.- means.hereinafter described, so. that it follows the movement.. ofthe collar:aadtraosmlts :the movement. to.Y inseln., and lever oolineotioa- Thelever ,9.4. is. rolaiiyoly; lona. as Compared to olio length of the. pinsupporting.; lever. S0. and it is,plv,otally mounted. upon the frame lbya soroiv 95.y asmaybo soon best from. Fisst 5 and 6.

The lover 9.9. which ispivotally mounted upon a. vertical. shait. Lilo.,isy ihereforemoyable over `rolatively largo angular distapoosfasCompaneo to the movement'of ythe lever 94'. 'Inisisdesimble .because ii.boon. found. ippraotioe, that it 1s essential, that. ille loverSibiransmittipe ibo mo,- iiop o. tbsv Collarv to. ibo indicator,travel', over 'considerable angular distances.` The shaft |011, uponwhich the lever 9 0 islpivotally mountcdris so located withv respectv tothe governor-l collar that the angle betweenthe lev'eparid face-'84 ofthe collar is quite large at both extremes of'move'- ment ofthe collar.Int-he constructiondisclosed theA angle .with the collar.v atits extremeright is somewhat. smaller than the anlg-xwhongtle collar yis at! itsextreme left, as -viewedin -1-"ig2 collar.4

' and the frictional forces that are created are transmitted direct-lyto the frame IS of the housing i upon which'the lever -94 is mounted, asclearly shown in Fig. 6. fr Rotation of the governor collar also exertsan Vupward force upon the lever 9:1y an'din order to prevent such forcefrom movingthe lever, there is provided aV substantially-right angledguide rail |02, which is adapted to bear relativelytlightly against theupper surface of the lever. The rail is so constructed and arrangedVthatV it"doe`s not prevent pivotal movement ofthe lever4 S4 about itsmounting. The rail isA suitablyr secured to a bracket iii-4 extendingsubstantiallyl axially of shaft 26 and aiiiXed to aY vertically disposedsupporting plate |05, supported in turn from a second verticallydisposed supporting plate |08 setor, for adjusting the relation of themovement ,f

of the indicator needle to the :movementl of Vthe The construction ofthe pin and lever connection and the adjusting means maybe ascertainedbest by reference to Figs. 2, 4 Yand 5.k Referring now to these figures,it may -be seen vthat the'lever @E is provided with a central relativelylong groove H4, whereby the lever .90 is made movablewith respect to theshaft lim and a Acollar "i E5 attached thereto'.A The collar supports afixed arm I I8 provided with' a groove |20 at one end thereof'forthe'reception of a part of the pin S8. -The `lever` 9B and arm ll'are,thereiore,`adjustable relativelto one another and are' normallymaintained in adjusted relationship by a locking screw |22 and a pair ofarms |24. When the locking screw |22 is'loosened, the length of thelever arm 90 may be vvaried by rotation of an adjusting screw |26rotatably mounted in a` projection |28 formedat the endof the lever andextending-at right angles therefrom and in threaded engagement with a'similar projeotion .|3, formed at'theadjacen'tend lof the arm H3. l I

'The angular movement of the sha-itY |30 is transmitted tothe'indicator' through a shaft |32 connected to the shaft |90 by afpairof gears |34 and |35 and to]r the pointershait |38, by a relativelylarge sector gearV H30' and a relatively small pinion 'gear' 42aiiixedrdirectly to the pointer shaft. 'The pointer shaft is rotatablymounted in the supporting plates |95 and Hi8.

A hair spring |44 is provided V'to 'return I the pointer to its minimumreading position (in this vcase 580 R. P. M.) which is determined bythesetting of a minimum reading stop |i8,threaded into a stud |58 mountedupon the supporting plate |05 and mounted to engagera pin IM mountedupon sector'gear|40. The shaft |32 is provided with a counterweight |52and is rotatably supported by the bracket ||2, which also supports thevertically disposed shaft |00, and `by the supporting plate |08.

The dial |6'iis protected by the usual glass plate |54 held in place vbyaY bezel l |58 suitably secured to the indicator frame. If desired, a

finished appearance-'to theY indicator housing may be' obtained bycovering a major portion thereof with a relatively thin metal cup-shapedshell |53, as lillustrated in Figs. l and 2.

lAfter thel finstrumenthas been assembled it Ymay 'be calibratedbyadjustment oi .the length of lever- 9@ or of the location of the weightsupport12 upon the governor'shaft. The iirst adjustment is accomplishedby first loosening the L flocking screw `|32 Vand then rotatingadjusting screw |26. The second adjustment .is effected by looseningscrew '14' and then shifting the weight support.

Upon installation of the instrument, as in an airplane' to indicateengine speed, the flexible shaft i2y is connected tothe engine andthegoverlnor shaft 26 is driven by the flexible shaft through the-helicalspring 44, inV a manner heretofore described in detail. The rotation ofshaft 25 at speeds proportional to the engine speed effects linearmovement of the governor collar 2S. Y j M Coming now to the descriptionof the operation Vof the 'means-for ltransmitting the movement ofthecollarfto Vthe indicator pointer and indicatorlshait, it may beseenthat the. shoe 92, interposedfbetween the flat face 84 of the collar02 and the pin E58, is maintained in'contact with the face by the pin 83which, in turn, is maintained in abutment withv the other side Yoi? theshoe '92 by the hair spring |44 acting through certain of the previouslydescribed gears and shaft.`v Consequently, as the weights S6 are `movedradially in response to variations in the speed;` ci the rotor shaft,the sleeve 18 ismoved accordinglyeither againstl or by the spring 86.

TheshoefSE is at all times maintained in Contact to thelever 04 andthroughit to the indicator frame. AVSincethe' angle between the leverand the face ofthe `collar isrelatively small, the frictional force islikewise decreased proportionately. Upward movement of the lever S4 isprevented by the guiderail |02 so that accurate readings are obtainableAat all times.

- The'above speoiiically-described embodiment of the inventionisillustrative and not limitative oi the invention; 'It' should beobvious to those skilled in theart thatv features of the present`invention are applicable not only tocentrifugally actuated tachometersbut to othertypes of indicators as I well. Furthermore, the particularcentrifugally"actuated tachometer may be modi- Viiedin various Wayswithout departing from the spiritl of the invention in' any way. y.

What I claim as' newv and desire to secure by 1. In an indicator, thecombination including, an indicator element, means including a pivot-`ally mounted element for imparting movement to said element,V and meansincluding a rotatable, axially movable member and a shoe mounted forindicator` element, and a support mounting said shoe independently ofand in contactV engagement with said pivotally mountedy element androtat.- able member, whereby frictionalorce created by contact betweensaid shoe and rotatable member are transmitted to said support.

l 2. In, an indicator, the combination including, anV indicator element,meansincluding a pivot- Vally mounted element for Vimparting movement tosaidindicator element, and means for actuating said pivotally mountedelement over a relatively wide angle in response to variations of acharacteristic to'be indicated, said means including a rotatable andaxially movable member, a shoe interposed between said member and saidpivotally mounted element, a pivotally mounted lever for supporting saidshoe independently'of said pivotally mounted element, said lever beingof a length and so arranged with respect to said rotatable and axiallymovable member that the angle between the latter and the lever isrelatively small as compared to the angular movement of said pivotallymounted element, and means Vfor maintaining said shoe in contact withsaid member, and said pivotally mounted element in contact with saidshoe during normal operation of the indicator l 3. In an indicator, thecombination including,

-an indicator element, means including a pivotallyv mounted element forYimparting movement to, said indicator element,andrmeans for actuatingsaid pivotally mounted element over a relatively wide angle in responseto variations of a characteristic to be indicated, said means includinga rotatable and axially movable member, a shoe interposed between saidmember and said pivotally mounted element, a pivotally mounted lever`for supporting said shoe, and means for maintaining said shoe incontact with said member, and said pivotally mounted element in contactwith said shoe during normal operation of the indicator, said pivotallymounted element being relatively short and movable over-considerableangular distances on each side of the line passing'through the pivotpoint of the element perpendicular to the axis of rotation of theyrotatable member,r said pivotally mounted lever being relatively long,whereby the shoe -is moved through relatively small angular distances ascompared to the movement of said element, and the pivot point oflsaidlever being located so that the angle between the lever and theface of the rotatable member against which said shoe bears l contactwith said shoe and said shoe in Contact with Asaid collar, whereby thecontact engagement of the shoe with said element and collar and theindependent mounting of the shoe prevent transmission of frictionalforces to said element.

5. In an indicator, the .combination including, a frame, an indicatorelement rotatablymounted v upon said frame, means including a leverpivotallyY supported by said, frame for ltransmitting movement tosaid'indicator element, and means foractuating saidlever over arelatively wide Vangle in response to variations of acharacteristic tobe indicated, said means including a rotatable and axially movablemember having a substantially at face, a shoe interposed between saidmember and lever andV adapted to abut against said face, al second leverpivotally mounted upon said frame for supporting ysaid shoarand meansfor maintaining said shoe in contact with said face,andsaidiirst-mentioned lever iii-contact with said shoe during normaloperation of the indicator, said Afirst-mentioned lever beingrelaf ltively short and movable over considerable angular Ydistances on eachside of a line passing through the pivot point of the lever andperpendicular t0 the axis of rotation or said member and thesecond-mentioned lever being relatively long, whereby the sho-e is movedthrough rela-Y tively small angular distances as compared to themovement of saidk element, and said secondmentioned lever being mountedpivotally upon said frame and its pivot point being located so that the,anglebetweenthe lever and the face of the rotatable member againstwhich said shoe bears is relatively small.

V6. yIn an indicator, the combination including, a frame, an indicatorelement mounted onA said frame, an element pivotally1 mounted on saidframe and mechanically connected to said indicator element for impartingmovement thereto, a shaft rotatable ata speed proportional to acharacteristic tov be' indicated mounted on said frame, a centrifugallyactuated collar rotatable with Yand slidable along said shaft inresponse to variations in said characteristic, said collar havingVarelatively smooth face, a shoe interposed Vbetween ysaid collar andelement, and adapted tov bear against said face, means pivotallymounting said shoe upon said frame independently of said collar andelement, and biasing meanszfor normally maintaining said element incontact with Vsa-idgshoe and said shoe in Contact with said collar, saidpivotallyv mounted element being movable over Va relatively wide anglewith respect to the face of said collar and said shoe-mountingmeans'being movable over a relatively small angle with respect to the,face of said collar.

r7. In an indicator, the combination including, an indicating element,means for imparting movement to said element, a rotatable member movableaxially alongits axis of rotation, a shoe, a pivotally mounted leversupporting said shoe between and independently of said member and means,means biasing'said first-mentioned meansV into contact with said` shoeand said shoe into Ycontact with said member, and means associated withsaid lever permittingr pivotal movement thereof and restrainingtransversamovement thereof occasioned by contact with said rotatablemember. ,l

8. In combination, a movement transmitting member pivotallyfmo'unted forangular movementin a predetermined plane, a member rotatable about anaxis substantially parallel to said plane and operable to Vactuate lsaidmovement transmitting member over a relatively wide angle, a shoelocated between and in contact with both said members, and meanssupporting saidshoe ,independently of both members, whereby frictionalforces created by rotationof said rotatable member in contact with saidshoe are transmitted to the shoe support. FREDERICK G. SCHWEISTHAL.

